Conventionally, this type of apparatus includes the following stereoscopic image display apparatus (see Patent Document 1, for example). As shown in FIG. 9, the stereoscopic image display apparatus includes two image display devices 102, 103, respectively serving to display an image for the left eye and an image for the right eye, and having a linear polarization plate with a horizontal polarizing direction. Further, a half mirror 105 is disposed in a slant position to extend from a corner formed between the two image display devices 102, 103 to an area between the two image display devices 102, 103. And a ½ wavelength plate 119 and a linear polarization plate 121 with a vertical polarizing direction are laminated in order on the front plane of a linear polarization plate 113 on the front plane of a display surface of the image display device 102.
According to this conventional apparatus, the light of an image displayed on the image display device 102 is emitted as once polarized horizontally by the linear polarization plate 113 with the horizontal polarizing direction. The light of the image has its direction of polarization rotated 90 degrees to change from the horizontal direction to the vertical direction by the ½ wavelength plate 119 and linear polarization plate 121 further arranged on the front plane of the linear polarization plate 113, and is reflected by the half mirror 105, whereupon the vertically polarized light of the image travels toward the observer. On the other hand, the light of the image displayed on the image display device 103 is emitted as horizontally polarized, and passes through the half mirror 105. The horizontally polarized light of the image travels as it is toward the observer. Of the lights of the images displayed on the two image display devices 102, 103 which are transmitted through and reflected by the half mirror 105 have different directions of polarization, i.e. one being vertical and the other being horizontal. Therefore, the observer sees with the right and left eye through glasses 129 with polarization plates which are linear polarization plates 129R and 129L with vertical and horizontal directions of polarization, respectively, thereby seeing parallax images distributed to the right and left eyes. Therefore, the observer can observe a stereoscopic image.
In a conventional apparatus, as shown in FIG. 10, when upper positions of images to be displayed are set to upper positions of image display devices 202, 203, the image display device 203 is usually disposed so that the upper position of the image display device 203 and the upper position of the image display device 202 are opposed to each other. And the image is displayed on the image display device 203 after a horizontal reversal, whereby the image displayed as reflected by a half mirror 205 can have vertical and horizontal directions matched with those of the image of the image display device 202 displayed as transmitted through the half mirror 205.